Patterning method employing half tone mask, array substrate and display device

A patterning method employing a half tone mask includes the steps of: successively forming a first thin film layer, a second thin film layer and a photoresist thin film layer on a substrate; exposing and developing the photoresist thin film layer by using a half tone mask plate; performing a first etching on the substrate that is exposed and developed; performing a second etching on the substrate that has been subject to the first etching; passivating the substrate that has been subject to the first etching; ashing the substrate that has been passivated; performing a third etching on the substrate that has been subject to the ashing and the second etching; and, stripping the substrate that has been subject to the third etching.